Method for testing thin rubber articles



Aug. 27, 1940. A. M. YoUNGs 2,213,113

METHOD FOR TESTING THIN RUBBER ARTICLES Original Filed March 30, 1959 M ko N\ Patented Aug. 27, 1940 UNITED STATES PATENT orrlcla:

METHOD Fon TESTING THIN RUBBER ARTICLES Arthur M. Youngs, Trenton, N. J., assigner to Youngs Rubber Corp. of N. J., Trenton, -N. J., a corporation of New Jersey c mm. (ol. 13-51) This invention relates to new and useful improvements in methods for testing thin rubber articles and more particularly for testing such articles for imperfections, such as holes and per- 6 forations therein, being a division of an application for United States Letters Patent Serial No. 265,018, filed March 30, 1939.

.concurrently with the drive on the part oi' government and various sociologie associations against venereal diseases, attempts are being Y made on the' part of manufacturers tol control the manufacture of rubber prophylactic articles and prevent the sale of such articles as may be defective or imperfect due to the presence of E holes or perforations therein.

With the foregoing in mind, the principal object of the present invention is to provide a novel and positive method for testing rubber prophylactic articles whereby any hole or perforation 2li therein, however small, may be readily observed or detected, thus permitting imperfect articles toy be rejected. L-

A still further object of the invention is to vprovide a method for testing articles of the type described which is entirely arcurate and foolproof.

rihese and other-objects of the invention and the various features thereof are hereinafter fully set forth and shown in the accompanying drawing, in which:

3o Figure l is a semi-diagrammatic view in per-= spective of one apparatus capable of carrying out the method of the present invention for testing thin rubber articles.

l Figure 2 is an enlarged transverse view in section on line t'i--2 through the upper run of the apparatus at the point of test; and

Figure 3 is a view showing the manner in which the present invention operates to afford visible detection of imperfections in the articles.

The present invention is based essentially upon the discovery that by stretching prophylactic articles of thinrubber over a mandrel or other supporting form and then immersing the same in a bath of liquid, the said liquid will pass through even the most minute hole or perforation in the article and spread over the interior surface thereof between said article and mandrel producing a comparatively dark spot or area which is readily perceptible to the human eye.

5o Referring now to the drawing, there is there illustrated one form of apparatus capable of carrying out the present method and, referring particularly to Figure 1 thereof, reference numeral l designates generally an endless conveyor lo of the chain type carried upon sprocket wheels 2 Vthe thin rubber articles.

and 3, movement of the chain conveyor being continuous and in the direction of the arrows. The sprocket wheel 3 is merely an idler and the chain I is driven by the sprocket 2 which is in turn driven from a motor 4 through a suitable 5 belt, chain or the like 9.

'I'he chain conveyor'l is of the nconventional articulated link type comprising pairs of side bars or links 8 pivotally connected to the adjacent or next pair of bars or links 8 by means 10 of a pinY i which also carries a. roller 8, interposed between said side bars or links t, for engagement with the teeth of the sprocket wheels 2 and 3 in the usual manner. -Rigidly secured to the pivot pins 'l at opposite ends thereof are @5 brackets 9 having a vertical leg 9a and fan upper outwardly projecting horizontal leg 9b. .Afbar or rod i9 is secured to the horizontal legs tb of each pair of brackets t so as to extend transversely of the chain conveyor i and beyond each 20 side thereof. v

, Pivotally connected to opposite ends of each cross bar it by means of a spindle li as at i2 for swinging movement in a plane perpendicular to the plane of travel of the chain i is a mandrel 25 or like support, designated generally as it, for As herein shown, the mandrels it comprise a body portion it of suity able material, such as metal, and a base or hub portion it of suitablematerial, such as rubber, 30

articles so that the latter are supported thereon in a relatively stretched state or condition, and said body is pressed or otherwise secured upon the adjacent end portion of the base or hub i5.

The body it is provided with one or more aper 4o tures it therein to permit air to pass therethrough from the interior of the articles when mounting the same thereon thus enabling said articles to snugly embrace the bodies without the entrapment of air therebetween and in order that 45 the thin rubber articles will be retained uniform= ly upon the mandrels i3 in thedesired state or degree of stretch said body portions it are each provided with a circumferential groove toward or adjacent the base end thereof. This groove 5@ is intended to receivethe usual bead provided at the open end of the rubber articles which are thus securely retained uniformly upon the mandrels and in the stretched state or condition required successfully to carry out the invention. 5

The base or hub portion I5 of the mandrel or support I3 is in the form of a relatively thick sleeve or tube and is journalled upon the pivotally mounted spindle II by means of suitable ball bearing structures I1 so as to permit rotation of the mandrels freely about said spindles. Thus the mandrel I3, including its main body and base portions I4 and I5, is free to rotate about the spindle II, and at the same time, by virtue of the pivotal connection I2 of the spindle II with the bar I0, is movable in a plane perpendicular to the plane of travel of the chain I.

'I'he several mandrels I3 are supported in the desired angular position laterally oi' the chain I by means of tracks or guides I8 disposed at either side thereof and in subjacent contact with the hub or base portion I5 of said mandrels, the tracks or guides I8 being stationary and having a friction surface I8a so that the mandrels I3 are caused to roll therealong and rotate about their supporting spindles II as they are advanced by the chain I.

The tracks or guides I3 ex'tend throughout the cycle or course of the chain I except for a relatively short length thereof in which the thin rubber articles are respectively mounted upon the mandrels I3 and subsequently removed therefrom, this station being located toward one end of the lower run of the course of the said chain I. The tracks or guides I8 are so positioned with respect to the chain I that their upper surfaces I8a support the mandrels I3 in a substantially horizontal position throughout the greater part of the chain course.

The thin rubber articles are manually stretched upon the mandrels, as hereinbefore described, during the course of travel of the chain I near the end of its lower run and at this loading station the hubs or bases I5 of the mandrels I3 leave the stationary tracks or guides I8 and are engaged by an endless belt I9. This belt I9 is carried upon main and auxiliary rolls 20 and ZI respectively so as to elevate the upper course of said belt I9 above the level`of the track or guides I8 and thereby elevate or incline the mandrels I3 upwardly at an angle of approximately 45 to facilitate mounting of the thin rubber articles thereon. Mounting of the articles upon thelmandrels I3 which rotate about their supporting spindles II is extremely dimcult and in order to prevent such rotation of said mandrels I3 during this loading stage, the belt I9 is driven in the direction of travel of the chain I and at exactly the same speed as said chain so that no rotation of the mandrels takes place while in contact with said belt I9, and to insure exact coordi.

nation and duplication of the speed of the chain I and belt I9, the latter is driven from the driving means of the former through a chain, belt or the like 22.

Upon leaving the belt I9, the mandrels I3, each with an article mounted thereon, engage the tracks or guides I8 and are supported thereby in a laterally projecting horizontal position in which position they are carried by the chain I about the sprocket wheels 2 into the upper run of the course where they traverse an open trough or tank 23 of suitable length and width. In this portion of the upper run overthe tank 23 the tracks or guides I8 converge gradually into closer spaced relation with respect to the chain I and their upper mandrel contacting surfaces I8a gradually decline outwardly and downwardly until they are disposed in a substantially vertical.

plane, thus permitting the said mandrels I3 t0 swing downwardly into the trough or tank 23 as shown in Figures 1 and 2 of the drawing. After the mandrels I3 have moved through the trough or tank a relatively short distance in the substantially vertical position shown in said Figure 2,

' the tracks or guides I8 and their upper surfaces gradually return to their previous relative positions thus causing the mandrels 3 to be gradually raised or swung upwardly out of said trough or tank 23 into horizontal position again for continucd movement through the course.

The trough or tank 23 is filled with a suitable liquid such as, for example, water, and upon immersion of the articles therein as above described.

the liquid will penetrate through even the smallest hole in an article and appear as a relatively dark, readily visible area in the region of said hole. In its normal condition the liquid, for example water, requires a period of time to penetrate the smaller holes which is of too great duration for practical commercial application of the invention for quantity production work and, in order that the water will penetrate even the smallest hole in an article in a few seconds time, I reduce the surface tension of the liquid to the desired extent or degree. This may be done by heating the liquid or adding thereto a predetermined quantity of a wetting agent such as, for example, Aerosol. In the practical commercial application of the invention, however, I both heat the water and also add thereto a small quantity of Aerosol; and very satisfactory results are obtained by the use of a bath of water maintained at a temperature between approximately F. to F. and to which has-been added a ten per cent solution of Aerosol at the rate of one ounce for each gallon of Water.

The bath is preferably of such depth and so spaced below the chain I that as the mandrels I 3 swing downwardly into the same, in the manner previously described, the articles mounted thereon are substantially entirely immersed in said liquid fora predetermined though comparatively short period of time and travel as shown in Figure 2 of the drawing.

During immersion and travel of the articles through the bath should any article be imperfect the liquid will pass or seep through the most minute hole or aperture in the article and spread out over the inner surface thereof between said article and its supporting mandrel and around such hole or perforation thus producing a comparatively darker spot or area, for example, as shown in Figure 3, which is readily perceptible to the eye, and enabling an observer or inspector discard that particular article because defec- While a particular embodiment of the invention has been herein illustrated and described it is not intended that said invention be limited thereto but that changes and modifications may be made and incorporated therein withinthe scope of the annexed claims.

I claim:

1. The method of testing thin rubber articles to detect imperfections therein, such as holes, which consists in mounting an article upon a. body arranged to support the same in a comparatively stretched condition, and then immersing said article thus mounted in a liquid bath for a predetermined period of time so that said liquid will pass through any hole in the article and spread over the underlying supporting surface of the body producing a comparatively dark area which is readily visible through said article.

2. The method of testing thin rubber articles to detect imperfections therein, such as holes, which consists in mounting an article upon a body arranged to support the same in a comparatively' stretched condition, and then immersing said article thus mounted in a liquid bath for a predetermined period of time, said bath being heated to a predetermined temperature to substantially reduce the surface tension thereof so that the liquid will pass quickly] through any hole in the article and spread over the underlying supporting surface of the body producing a comparatively darker area which is readily Visible through said article. n

3. The method of testing thin rubber articles to vdetect imperfections therein, such as holes, which consists in mounting an article upon a body arranged to support the same in a comparatively stretched condition, and then immersing said article thus mounted in a liquid bath for a predetermined period of time, said liquid bath having a predetermined. quantity of a wetting agent added thereto to substantially lower its surface tension so that the liquid will pass quickly through any hole in the article and spread over the underlying supporting surface of the body producing a comparatively darker area which is readily visible through said article.

4. The method of testing thin rubber articles to detect imperfections therein, such as holes, which consists in supporting a series of said articles in a relatively stretched condition, ad.- vancing said series of supported articles through a predetermined path of travel and immersing said supported articles in a liquid bath for a pre1 determined portion of said travel so that said liquid will pass through any hole in the article and spread over the underlying` supporting surface of the body producing a comparatively dark area which is readily visible through said article.

5. 'Ihe method of testing thin rubber articles to detect imperfections therein, such as holes, which consists in supporting -a series of said articles in a relatively stretched condition, advancing said series of supported articles through a predetermined path of travel and immersing said supported articles in a liquid bath for a predetermined portion of said travel, said bath being heated to a predetermined temperature to substantially reduce the surface tension thereof so that the liquid Will pass quickly through any hole in the article and spread over the underlying supporting surface of the body producing a comparatively darker area which is readily visible through said article.

6. The method of testing thin rubber articles to detect imperfections therein, such as holes, which consists in supporting a series of said articles in a relatively stretched condition, ad-

vancing said series of supported articles through a predetermined path of travel and immersing said supported articles in a liquid bath for a predetermined portion of said travel, said liquid bath having a predetermined quantity of a wetting agent added thereto to substantially lower its surface tension so that the liquid will pass quickly` through any hole in the article and spread over the underlying suppoiting surface ofthe body producing a comparatively darker area which is readily visible through said article.

ARTHUR M. YOUNGS. 

